JPH0243767A - Solid-state image sensing element forming wafer - Google Patents

Abstract

PURPOSE:To protect a photodetecting face of a CCD image sensor section against dust and dirt when a wafer, provided with the image sensor formed on it, is conveyed as a semi-fabricated product by a method wherein effective chip regions of solid-state image sensing elements formed on the wafer are covered with a peelable protective film respectively. CONSTITUTION:In a wafer 1 provided with two or more solid-state image sensing elements 2, which are composed of two or more pixels, convert light rays incident on the pixels into signals, and successively extract the converted signal by each pixel to obtain an output signal, the effective chip regions of the solid- state image sensing elements 2 formed on the above wafer 1 are covered with a peelable protective film 4 respectively. For instance, a mosaic color filter is formed as an on-chip filter on the wafer provided with the solid-state image sensing elements, and then the effective chip regions or the regions, where the chips of the solid-state image sensing elements are formed, are coated with peelable coating material (coating material excellent in releasability) through a screen printing or the like for the formation of protective films 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a solid-state image sensor formed wafer that can prevent contamination on the surface of the solid-state image sensor chip area in a wafer on which a plurality of solid-state image sensors are formed before dicing. It is related to.

[Conventional technology]

In recent years, with the remarkable development of integrated circuit technology, solid-state image sensors (mainly CCD image sensors and the like) have become mainstream as image sensors used in television cameras and the like. Here, to briefly explain the basic configuration of a CCD image sensor, a plurality of pixels and a shift register are formed on a semiconductor substrate, each consisting of a photosensitive element, a switching element, and a capacitor, and the amount of light of an input image received by each pixel. A charge corresponding to the pixel is generated by the photosensitive element of each pixel and stored in the capacitor of each pixel as a pixel signal, and the switching element of each pixel is controlled to convert the accumulated charge of each pixel for one line into the capacitor for one line. The image signal is obtained by transferring the image signal to a shift register with a 3D image signal and serially sending it out from this shift register.

FIG. 3 is a diagram showing a schematic configuration of a CCD image sensor, in which (a) is an analog transfer scan, line address transfer type configuration, and (b) is a frame transfer type configuration, (11,)
respectively indicate interline transfer type configurations. Among these, in the analog transfer scanning and line address transfer type configuration of (a), each pixel PC accumulates signal charges in a charge accumulation operation for a certain period, and then selects one of the two-dimensionally arranged pixel groups to be read out. In response to a command from the vertical scanning shift register vS that specifies the row position to be read out, the pixel group at the commanded row position operates as an analog shift register, and sequentially moves the accumulated signal charges to the right side of the diagram. The signals arriving at the right end are sequentially sent out by the column-oriented analog shift register VR and sent to the output terminal OU.
Lead to T. Next, the second pixel row [1] is selected by a command from the vertical scanning shift register 1S, and the signal charge is similarly guided to the output terminal OUT. Also (b
) has a frame transfer type configuration in which the upper half region is the image region IM and the lower half region is the signal charge accumulation region CI. There is a pixel group, and after a charge proportional to the incident light information is stored in each pixel for a certain period of time, the signal charge of each pixel PC is transferred to the storage area CH, thereby eliminating the signal charge. The pixels in the image area are caused to accumulate the next signal charge. The storage area C11 has the same number of element groups as the number of pixels in the image area IM having a transfer/storage function, and has the same number of element groups as the number of pixels in the image area IM.
After the signal charges of all pixels are stored here, one pixel is sent from the storage region CH to the horizontal analog shift register IIH for each column of pixels. The horizontal analog shift register HR has a capacity equal to the number of pixel columns, and by receiving signal charges for each pixel column one by one, it obtains an image signal for one line, and serially sends out the signal charge for one line. Obtain image signals for lines. By repeating such operations for the number of rows, scanning equivalent to X-Y scanning readout using an electron beam in an image pickup tube (this is called a frame transfer method) is performed.

In addition, in the interline transfer type configuration (C) above, the locations for photoelectric conversion and signal transfer are different, and the photoelectric conversion area becomes the field of view of the pixel PC, and the photoelectric conversion area is the field of view of the pixel PC. A light receiving section is provided at the position, and the light receiving section stores a signal charge proportional to the incident light information for a certain period of time, and this signal charge is transferred to a capacitor corresponding to the number of pixels in the column direction provided adjacent to each column in the column direction pixel group. This transfers the signal charge of each pixel PC to the vertical analog shift register VR corresponding to each pixel PC, and transfers the signal charge of each pixel PC to the next pixel PC with no signal charge. Accumulates signal charges. Vertical analog shift register VR for each column-to-window
sends signal charges for one pixel to each column-to-window position of the horizontal analog shift register IIR to obtain an image signal for one line, which is then serially sent to obtain an image signal for one line.

By repeating such operations for the number of rows, a scan equivalent to readout in XY scan using an electron beam in an image pickup tube is performed.

In addition, among solid-state image sensors for single-chip color cameras that have been widely used in recent years, there is an on-chip filter type in which a color filter is formed directly on the element. A combinable interline transfer type CCD (hereinafter referred to as IT-COD) is often used. This IT-COD has the configuration as explained in FIG. 3(C), and uses, for example, a photodiode as the light receiving section in each pixel, and a storage diode as a capacitor for accumulating the output of this photodiode. , a vertical transfer CCD is used as the vertical analog shift register IIR. A shift gate is used to control the sending of the signal charge of the output of the photodiode accumulated in the storage diode to the vertical transfer CCD, and this shift gate also serves as a transfer electrode for the vertical transfer COD.

In IT-COD, each of a plurality of mutually independent pixels arranged two-dimensionally has a light receiving section, a storage capacitor, and a vertical transfer CCD which is a readout section for reading out and transferring signal charges accumulated in the capacitor. Become. Since this vertical transfer CCD portion is optically shielded, it becomes a sensitivity ineffective area, and the field of view for each pixel is limited to the area occupied by the light receiving section, resulting in poor detection efficiency. Therefore, in order to make effective use of this sensitivity invalid area, an amorphous silicon (A-8I) layer for photoelectric conversion is laminated over the entire pixel area including the sensitivity invalid area, and the generation by light incident on this amorphous silicon layer is CCDs with an amorphous silicon multilayer structure have also appeared in which charge signals are accumulated in the accumulation portions of corresponding pixels and taken out.

[Problem to be solved by the invention]

Incidentally, such CCD image sensors having various structures are formed on a semiconductor wafer by processing a plurality of chips at a time according to a predetermined semiconductor process. and,
After forming the on-chip color filter, this semiconductor wafer is machined with scribe grooves, which are dividing grooves for separating each CCD image sensor chip, located on the outer periphery of each CCD image sensor chip. In the final process, the semiconductor wafer is divided along scribe grooves (dicing), fixed on a support substrate, and wire bonded to complete the device.

By the way, when forming an on-chip color filter, CCD image sensors for multiple chips are formed on a semiconductor wafer, and the R of each CCD image sensor is
(red), G (green), and B (blue) pixels.In the red filter formation process, a blue filter is formed only on each red pixel, and in the green filter formation process, a blue filter is formed only on each line pixel. Then, each blue pixel is shipped as a semi-finished product with a dyeable transparent film, and in the final process, the semiconductor wafer is diced along the scribe grooves, fixed on a support substrate, and wire bonded. Complete it as an element.

When forming on-chip color filters in this way, it is necessary to form a dyeable transparent filter base and dye it, and this filter formation process is different from normal semiconductor manufacturing processes. In addition to dyeing, resist dyeing involves the process of dyeing, and in addition to dyeing, a resist dyeing film is applied to the dyed filter so that it will not be affected by the dyeing of filters of other colors that are about to be dyed. Since a process for resisting dyeing such as chemical treatment is also included, an on-chip color filter manufacturing process is required in addition to the normal semiconductor element manufacturing process, and these processes are completely separated. Therefore, a wafer with multiple CCDC soy sensors manufactured using a semiconductor manufacturing process is transported to a factory for on-chip color filter manufacturing process, where filters are formed, and then transported to a final process factory for mounting and finishing. It is necessary to say that.

A problem that arises during this transportation process is dirt on the CCD pixel surface. In particular, in recent years, with the miniaturization of pixels, the accompanying miniaturization of on-chip color filters, and strict requirements for the optical properties of filters, it is necessary to excel in semiconductor manufacturing technology and dyeing manufacturing technology in order to maintain high quality. In the printing industry, it is necessary to transport CCD image sensor wafers with on-chip color filters formed as semi-finished products, but since the CCD image sensor is an image sensor, the light-receiving surface is exposed. If dust or dirt adheres to it, it may cause element failure. When transporting a wafer as a semi-finished product, it is extremely difficult to completely protect the exposed light-receiving surface from dust and dirt.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to protect the light-receiving surface of the CCD image sensor portion from dust and dirt when a wafer on which a CCD image sensor is formed is transported as a semi-finished product, and also to protect the light receiving surface of the CCD image sensor portion from dust and dirt. An object of the present invention is to provide a solid-state imaging device forming wafer that is easy to handle.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. In other words, a plurality of solid-state image sensors are formed, each consisting of a plurality of pixels, which converts the light incident on the light-receiving surface of these pixels into a signal, and sequentially extracts the converted signal for each pixel to obtain an output signal. In the wafer, each effective chip area of each of the solid-state image sensors formed on the wafer is coated with a peelable protective film.

[For production]

In such a configuration, the effective chip area of each of the solid-state image sensors on the Ueno 1 formed by forming a plurality of solid-state image sensors is covered with a peelable protective film, and this protective film protects against dust and dirt. This prevents the liquid from directly adhering to the surface of the solid-state image sensor formation area. Since the protective film is peelable, it is easy to peel off and does not stick to the surface of the solid-state imaging element formation area, so if the wafer is peeled off after each solid-state imaging device is divided, it can be removed during transportation. It is possible to reliably protect the device from dust and dirt, and to prevent element failure due to adhesion of dust and dirt.

Therefore, it cannot be covered with an oxide film, etc.
When transporting a solid-state imaging device such as a COD image sensor, which has a special area called the light-receiving surface, as a semi-finished product, the light-receiving surface of the solid-state image sensor must be protected from dust and dirt. It is possible to provide a solid-state imaging device-forming wafer that can be reliably protected and is also easy to handle in subsequent steps.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

This is an image element forming wafer, and a plurality of solid-state image sensors 2 are formed in an orderly manner on this wafer 1 by a semiconductor device manufacturing process. Then, scribe grooves 3, which are dividing grooves for separating the plurality of solid-state image sensors 2, are formed by cutting vertically and horizontally using the gaps between the solid-state image sensors 2, and are formed in a later process. This scribe groove 3
By dividing the wafer 1 along the
Separate. Note that 2a is a light-receiving surface of the solid-state image sensor 2.

For example, on the solid-state image sensor forming wafer 1 as shown in (a),
After forming the mosaic color filter as an on-chip filter, as shown in FIG. A peelable coating material (coating material with good releasability) is coated on the area of the removed portion to form a protective film 4. Since the effective chip area of each solid-state image sensor 2 is relatively wide, this coating can be applied only to the necessary area using screen printing technology or the like.

Here, care must be taken to ensure that the peelable coating material is not applied to the scribe grooves 3, which are grooves for separating the plurality of solid-state image sensors 2. This is because when a peelable coating material is applied to the scribe groove 3, a part of the protective film 4 of the solid-state image sensor 2 will enter the scribe groove 3, and the protective film 4 will be peeled off during dicing. This is to prevent it.

In this way, the effective chip area of each solid-state image sensor 2 in the solid-state image sensor forming unit/\-1 is coated with a peelable coating material, and the protective film 4 is transported to a factory for subsequent processing. The wafer 1 is diced and separated into individual solid-state image sensor chips in a factory. After mounting the separated solid-state image sensor chip on a support substrate, the protective film 4 on the chip of the solid-state image sensor 2 is peeled off as shown in FIG. 2, and wiring is performed to complete the solid-state image sensor. The protective film 4 is formed on the effective chip area of the solid-state image sensor 2, and is therefore formed outside the light-receiving surface 2a and in an area that does not cover the scribe grooves, so it will not peel off during dicing. Furthermore, during peeling, the light-receiving surface 2a can be peeled off without touching it.

In this way, this device is a solid-state device that is composed of a plurality of pixels, converts the light incident on the light-receiving surface of these pixels into a signal, and sequentially extracts the converted signal for each pixel to obtain an output signal. In a wafer on which a plurality of image sensors are formed, the effective chip area of each of the solid-state image sensors formed on the wafer is coated with a peelable protective film. By coating the effective chip area of each of the solid-state image sensors on the wafer with a peelable protective film, this protective film prevents dust and dirt from directly adhering to the surface of the solid-state image sensor forming area. do. And since the protective film is peelable, it is easy to peel off.
Because it does not stick to the surface of the solid-state image sensor formation area,
By peeling and removing Ueno 1- after dividing each solid-state image sensor, it is possible to reliably protect it from dust and dirt during transportation, and it is possible to prevent element failure due to adhesion of dust and dirt.

Therefore, when transporting a wafer as a semi-finished product on which a solid-state imaging device such as a CCD image sensor is formed, it has a special area called a light-receiving surface that cannot be covered with an oxide film or the like and must be protected from contamination. The light-receiving surface of the image pickup element can be reliably protected from dust and dirt, and furthermore, there are advantages in that it becomes easier to handle in subsequent steps.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications within the scope of the gist thereof.

〔Effect of the invention〕

As described in detail above, according to the present invention, element failure due to adhesion of dust and dirt can be prevented, and therefore,
When transporting a wafer as a semi-finished product on which a solid-state image sensor is formed, which has a special area called a light-receiving surface that cannot be covered with an oxide film or the like and must be protected from contamination, the light-receiving surface of the solid-state image sensor portion must be It becomes possible to provide a solid-state imaging device-forming wafer that can be reliably protected from dust and dirt and is also easy to handle in subsequent steps.

[Brief explanation of the drawing]

Figure 1 is a diagonal diagram for explaining one embodiment of the present invention, Figure 2 is a diagram showing the process of peeling off a protective film, and Figure 3 is a schematic diagram of a conventional general CCD image sensor. FIG. 3 is a diagram for explaining the configuration. DESCRIPTION OF SYMBOLS 1... Solid-state image sensor formation wafer 2... Solid-state image sensor, 2a... Light-receiving surface, 3... Scribe groove, 4...
··Protective film. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A wafer on which a plurality of solid-state image sensors are formed, each consisting of a plurality of pixels, which converts the light incident on the light-receiving surface of these pixels into a signal, and which sequentially extracts the converted signal for each pixel to obtain an output signal. A solid-state imaging device formed wafer, characterized in that each effective chip area of each of the solid-state imaging devices formed on the wafer is covered with a peelable protective film.